The aim of Ethereum Merge is to improve the speed, efficiency, and scalability of the Ethereum network so that it can process more transactions and provide a higher level of security.
Ethereum currently runs Proof-of-Work and Proof-of-Stake chains in parallel.
Both chains have validators, but only PoW processes users’ transactions. With the upgrade, Ethereum will move to a PoS chain called the Beacon Chain.
Thanks to the ETH Merge, mining will lose its relevance — accordingly, the infrastructure will become more environmentally friendly.
The reason the change from PoW to PoS is called “the Merge” is because the already running beacon chain will merge with the existing Ethereum mainnet chain. This preserves the history of the network, its functionality, but crucially changes the consensus mechanism. The beacon chain will coordinate data and the production of new blocks via network validators, which will use economic incentives to secure the blockchain.
Architecturally, the Merge is making use of the existing technology in Ethereum and supplementing it with what we need for the future. Current Ethereum clients, like Hyperledger Besu, will become known as “execution clients” and will handle state storage, block production, and smart contract interactions. “Consensus clients,” like Teku, will handle synchronizing state across the network and submitting transactions to the beacon chain. A new piece of technology called the “engine API” will allow these two clients to talk to each other extremely efficiently. All together, this new stack powers PoS with existing technologies and formats (like JSON RPC) and new ones such as REST APIs for the consensus clients.
The Merge will not solve scalability challenges right away, but is set to pave the way for sharding to improve data-availability and bandwidth. Users should look to rollups and L2s to scale immediately and lower gas fees.